Back in early October, the Queen’s personal assistant, adviser and curator Angela Kelly announced that she would be writing a book on Her Majesty.

With the monarch’s personal blessing, Kelly penned DressingThe Queen: The Jubilee Wardrobe. Published by The Royal Collection, Kelly’s book recounts preparations for the Diamond Jubilee year, which celebrated the Queen’s sixty years on the throne.

Much like the Duchess of Cambridge did with the Royal School of Needlework, Kelly kept her staff in the dark about details surrounding the Olympics Opening Ceremony skit. As one of the few people who knew about the big reveal, Kelly worked with director Danny Boyle.

“The Buckingham Palace dressmakers worked quietly for months, never having both dresses out of storage at the same time,” Kelly wrote. “Even they didn’t know why two dresses were required for the same event.”

For the Diamond Jubilee Concert on June 4th, Kelly made the Queen’s dress out of fabric bought in 1961, according to an excerpt in the Daily Express. The color and dramatic style were inspired by the Queen Victoria Monument, on which the concert took place in front of Buckingham Palace.

Fact: “After 6pm the Queen does not usually wear a hat but may wear a headpiece, and to the evening state banquets, a tiara,” Kelly wrote.